Controlled dosage syringe



Feb. 25, 1964 L. G. DAMGAARD 3,122,281 Q CONTROLLED DOSAGE SYRINGE FiledSept. 24, 1962 INy T R.

$70M; v s

United States Patent Office 3,122,28l Patented Feb. 25, 1964 3,122,281CONTROLLED DOSAGE SYRWGE Laurits Gudmund Damgaard, Virum, Denmark,assignor to H. Struers Chemiske Lahoratorium, Copenhagen, Denmark FiledSept. 24, 1962, Ser. No. 225,693 Claims priority, application DenmarkOct. 6, H61 3 Claims. (Cl. 222-309) This invention relates to acontrolled dosage syringe of the type comprising a cylindrical barrel, aplunger slidable in said barrel, and cooperating means mounted on saidbarrel and on said plunger for withdrawing the latter from its forwardposition in said barrel, and for adjustably limiting the movement ofwithdrawal.

A syringe of the type referred to serves to eject a predetermined volumeof liquid, which is rendered possible by the fact that the stroke of theplunger is determined between its fully forward position in the barreland its withdrawn position, the latter being defined by the said meansfor adjustably limiting the movement of withdrawal.

Syringes of the type referred to are known in which a clamping member isattached to the barrel of the syringe, said clamping member having twocolumns which at their other end are connected by means of a traversecarrying a set screw. Another traverse constructed with holes for thecolumns is attached to the head of the plunger. Tensional springs areconnected between the ends of the two traverses.

While this known construction serves the purpose for which it isintended-seeing that it limits the movements of the plunger ratherreliably between the end bottom of the barrel and the top of the setscrew-it nevertheless suffers from certain drawbacks. Thus, theoperation of the syringe is somewhat inconvenient because the set screwis located directly at the place where the thumb should preferably beapplied to the head of the plunger in order to push the plunger forward.Moreover, the construction is rather stiff so that jamming of theplunger in the barrel may easily occur if the columns are not accuratelyparallel to the cylinder. To remedy the drawbacks of the stillconstruction, packing material may be used in attaching the clampingmember to the cylinder, partly in order to adjust the columns to theglass which in practice cannot be made with a very high degree ofaccuracy, partly in order to secure adequate clamping without breakageof the glass. However, the use of soft packing material has the drawbackthat the apparatus will not be very resistant to boiling andsterilization. The known syringe referred to is very difficult todisassemble for cleaning purposes and when such disassembling isperformed, the setting of the volumetric capacity is lost so that uponreassembling the syringe, the set screw must be adjusted anew. This is aconsiderable drawback since setting of the volumetric capacity maysometimes be a rather complicated operation involving checking by aweighing operation, .while on the other hand frequent cleaning is inmany instances required because the clearance between the cylinder andthe plunger is so small that the presence of a small particle ofextraneous matter may suifice to stop the movement. Owing to the stificonstruction, only an expert will be capable of replacing the glassparts in the case of breakage. Finally, it is to be mentioned that it isdifiicult to avoid a lopsided pull on the plunger because this wouldrequire that the springs should be of absolutely equal strength.

It is an object of the invention to eliminate the described drawbacks.To this end, according to the invention, a controlled dosage syringe ofthe type referred to comprises a cylindrical barrel, a plunger slidablein said barrel, a single column attached to said barrel and located in aposition parallel to and spaced from the rearward extension of thegeometrical axis of said valve, an operating member attached to saidplunger at the rearward end thereof, said operating member having aradially extending arm constructed with a lateral notch in a positionand of a size to engage around said column at a clearance, saidoperating member further having a looped portion extending opposite tosaid arm and looped rearwardly to a point in the rearward extension ofthe axis of said barrel, an arm extending from said column adjacent therear end thereof to a point in the rearward extension of the axis ofsaid barrel, a spring located in the rearward extension of the axis ofsaid barrel and connecting said looped portion of said operating memberand said arm of said column, and adjustable stop means on said columnfor cooperation with said arm of said operating member.

In this construction, the stop means are displaced from the cylinderaxis so that they do not form an obstacle to the placing of a thumb onthe middle of the head of the plunger. Moreover, it is possible byturning the plunger and the operating member attached thereto about thecylinder axis to liberate the operating member and thereby the plungercompletely from the parts attached to the cylinder so that the syringemay easily be disassembled without disturbing the setting of the stopmeans. Owing to the clearance at which the notch of the arm of theoperating member engages around the column, the plunger is freelymovable relative to the cylinder within sufficient limits to permit itto adjust itself to the cylinder so as to avoid jamming, i.e. thestiffness of the known construction referred to is eliminated. Moreover,the two symmetric springs of the known construction have been replacedby a single spring located in the axis of the cylinder so that thedanger of lopsidedness of the spring force acting on the plunger hasbeen eliminated.

In a preferred embodiment of the invention, a locking member is providedwhich is slidable onto and withdrawable from the end of said arm of saidoperating member in a radial direction with respect to the barrel axis,said locking member having curved sliding faces for engaging said columnin the locking position of said locking member. The said locking memberserves to prevent unintentional disengagement of the operating memberfrom the column, and at the same time the curved sliding faces of theoperating member will secure smooth sliding of the arm of the operatingmember along the column.

Smooth and noiseless sliding of the arm of the operating member alongthe column may therefore be obtained, even if the column is screwthreaded. It is therefore possible, according to the invention, toconstruct the stop means in a particularly simple and reliable manner,viz. in the form of a nut with locking nut in screw threaded engagementwith the column.

One embodiment of the invention will now be described in further detailwith reference to the accompanying drawing in which FIG. 1 shows thesyringe in side view,

FIG. 2 on a larger scale, a section along the line II II in FIG. 1,

FIG. 3 likewise on a larger scale, part of an operating member of thesyringe, and a locking member slid halfway into position on saidoperating member, and

FIG. 4 the locking member of FIG. 3 as viewed from the left-hand side inthat figure.

In the drawing, -1 is the cylinder or barrel of a dosage syringe, and 2the plunger of the syringe. The cylinder 1 has a collar 3 against whichtwo discs 4- and 5 are clamped from opposite sides. A threaded column 6is operating member along the latter.

attached to the disc 5 in a position parallel to and spaced from therearward extension of the cylinder axis.

The plunger 2 is constructed at its rear end with a head 7 to which anoperating member 8 is attached by means of a U-shaped clip member 9which engages below the head of the plunger and is elevated from theoperating member by means of a lever 10 welded to the operating memberand pressed upwards by means of a screw 11. The operating member 8 has aradially extending arm constructed with a notch 12 in a position toengage around the column 6. The notch 12 has such dimensions as toengage the column 6 at a considerable clearance in a radial directionrelative to the cylinder axis. The arm of the operating member is lockedrelative to the column 6 by means of a locking member 13 adapted to heslid onto the arm 8' of the operating member from the end thereof. Forthis purpose, the locking member 13 has two guides 14 and 15 adapted tobe slid onto the marginal edges of the arm 8' of the operating member,whereby one of these guides will .close the notch 12. Below the guides14 and 15, the locking member is constructed with curved sliding faces16 and 17 engaging with the column and thereby securing smooth slidingof the The locking member is made from resilient material so that it iseasy to slide onto the end of the arm 8' of the operating member. Thelocking member does not make the construction stiff since it is capable,owing to its resiliency, of following the column even if the latter isnot accurately parallel to the axis of the cylinder.

Opposite to the arm '8, the operating member 8 is constructed with alooped portion 8". A spring 19 tending to .pull the plunger rearwardlyrelative to the cylinder is connected between the rear end of the saidlooped portion 8 and an arm 18 extending from the rear end of thecolumn. The spring 19 is located in the rearward extension of the axisof the cylinder 1. On the column, a setting nut 20' with a locking nut'21 is provided in screw threaded engagement therewith. The setting nut20 serves to obtain .an accurate limitation of the movement ofwithdrawal of the plunger by' engagement of the arm 8' of the operatingmember 8 with the bottom face of the setting nut 20.

When the locking member 13 is removed, the plunger may be rotated -inthe cylinder to liberate the operating member from the column and thenuts 20 and 21 so that the plunger may be withdrawn and removed forcleaning purposes without disturbing the setting of the nuts.

In order to obtain easy detachment of the spring connection between theoperating member and the column when the plunger is to be Withdrawn, thearm 18 con-' to and spaced from the rearward extension of the geo-.

metrical axis of said barrel, an operating member attached to saidplunger at the rearward end thereof, said operating member having aradially extending 'arm constructed with a lateral notch in a positionand of a size to engage around said column at a clearance, saidoperating member further having a looped portion extending opposite tosaid arm and looped rearwardly to a point in the rearward extension ofthe axis of said barrel, an arm extending from said column adjacent therear end thereof to a point in the rearward extension of the axis ofsaid barrel, a spring located in the rearward extension of the axis ofsaid barrel and connecting said looped portion of said operating memberand said arm of said column and adjustable stop means on said column forcooperation -with said arm of said operating member.

2. A syringe as in claim 1, and further comprising a locking memberwhich is slidable onto and withdrawable from the end of said arm of saidoperating member in a radial direction with respect to the barrel axis,said locking member having curved sliding faces for engaging said columnin the locking position of said locking member.

3. A syringe as in claim 1 in which said column is screw threaded, andsaid stop means consist of a nut with locking nut in screw threadedengagement with said column.

References Cited in the file of this patent UNITED STATES PATENTS2,198,666 Gruskin Apr. 30, 1940 FOREIGN PATENTS 46,042 France Feb. 15,1936 (Addition to No. 783,520) 733,168 Great Britain July 6, 1955984,352 France July 5, 1951

1. A CONTROLLED DOSAGE SYRINGE COMPRISING A CYLINDRICAL BARREL, APLUNGER SLIDABLE IN SAID BARREL, A SINGLE COLUMN ATTACHED TO SAID BARRELAND LOCATED IN A POSITION PARALLEL TO AND SPACED FROM THE REARWARDEXTENSION OF THE GEOMETRICAL AXIS OF SAID BARREL, AN OPERATING MEMBERATTACHED TO SAID PLUNGER AT THE REARWARD END THEREOF, SAID OPERATINGMEMBER HAVING A RADIALLY EXTENDING ARM CONSTRUCTED WITH A LATERAL NOTCHIN A POSITION AND OF A SIZE TO ENGAGE AROUND SAID COLUMN AT A CLEARANCE,SAID OPERATING MEMBER FURTHER HAVING A LOOPED PORTION EXTENDING OPPOSITETO SAID ARM AND LOOPED REARWARDLY TO A POINT IN THE REARWARD EXTENSIONOF THE AXIS OF SAID BARREL, AN ARM EXTENDING FROM SAID COLUMN ADJACENTTHE REAR END THEREOF TO A POINT IN THE REARWARD EXTENSION OF THE AXIS OFSAID BARREL, A SPRING LOCATED IN THE REARWARD EXTENSION OF THE AXIS OFSAID BARREL AND CONNECTING SAID LOOPED PORTION OF SAID OPERATING MEMBERAND SAID ARM OF SAID COLUMN AND ADJUSTABLE STOP MEANS ON SAID COLUMN FORCOOPERATION WITH SAID ARM OF SAID OPERATING MEMBER.